The following description provides a summary of information relevant to the present invention. It is not an admission that any of the information provided herein is prior art to the presently claimed invention, nor that any of the publications specifically or implicitly referenced are prior art to the invention.
The immobilization of oligonucleotides on substrates is an important and necessary step for many applications such as DNA chip technology, surface plasmon resonance experiments, or other bio-sensor applications. Classically, oligonucleotides are immobilized onto substrates by modification of the 3′- or 5′-end with one reactive group. Oligonucleotides have been modified with a terminal amine, thiol or aldehyde (for covalent attachment) or a group capable of forming stable complexes e.g. biotin, phenylboronic acid etc. (for noncovalent attachment). The modified oligonucleotides are then placed at the location where the immobilization is desired and reacted with an appropriate functional group on the substrate, such as an aldehyde, maleimide, etc., or complexed with a binding molecule such as streptavidin, etc. Placing at specific locations on a substrate can be done by mechanical spotting or spraying (pin or drop deposition), by electronic addressing, or by a variety of other processes. In some cases the reaction for the immobilization is slow and requires long (overnight) incubation of the oligonucleotides on the substrate. These immobilization reactions may also be reversible, resulting in the release of the macromolecule over time.
In other contexts, dendrimeric structures on macromolecules has been described (e.g., WO 99/10362, WO 96/19240, and WO 99/43287). However, these uses of dendrimeric structures have focused on providing signal sites, such as for detection, while the macromolecule itself is simply attached to any substrate present by using classical means.